# All Questions

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107 views

### Could ingenuity survive if Perservance failed?

They both landed successfully and ingenuity was deployed. Perserverance drove away, and then failed. Could ingenuity survive on its own?
80 views

### Why aren't clusters of F-15 or SR-71 engines used for a boost stage for rockets? [duplicate]

A cluster of say 8 F-15 or SR-71 engines in my mind could make a viable first stage for a small rocket. Second they can land the stage back to the ground and if my guess is right they could go to up ...
654 views

I recent asked this question. There, I was also linked to this other question. Both, however could benefit from the answer to one fundamental. What is "aerospace grade"? If sometimes ...
1 vote
52 views

### Historical Moon’s True Anomaly Numbers

What are moon’s true anomaly angles for new moons in year 1994? Cannot find historical true anomaly numbers on the internet.
52 views

### Repeat ground track with 1 day repetition

I'm struggling with a doubt regarding repeating ground tracks (RGT). I've a satellite in a LEO circular orbit with a predefined non-polar inclination (64°) and I want to determine the needed semi-...
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65 views

### Mars planet exploration [duplicate]

Ultralight Helicopters As part of Mars planet exploration, could there be aviation i.e. airplanes, helicopters flights possible on the planet?
118 views

### What if Perseverance had experienced a fault after dropping Ingenuity?

When Ingenuity was released on the Martian surface in April 2021, Perseverance had to drive away to let the helicopter recharge its batteries with its solar panel. Was there a concern that the rover ...
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48 views

### Reaction control system testing

How are RCS (reaction control systems) for Launch vehicles usually tested? After going through some literatures, I came across two different testing schemes, Leans more towards testing the Cold gas ...
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3k views

### What makes aluminum aerospace grade?

So what is aerospace grade aluminum? Aerospace grade and regular aluminum or both aluminum. Do they have a different composition or strength? What makes one aerospace grade?
132 views

### Is there any chance that Opportunity survived, but NASA kept pinging it at the wrong time?

In 2018, NASA's beloved little Opportunity (oppy) was declared dead after a dust storm "killed" it. It may still be OK, but when NASA began recovery effort, they pinged oppy when it was ...
90 views

### How does US crewed launch abort coverage "jump" the ocean in an instant?

As I understand things, the Commercial Crew Program stipulates full abort coverage from pad to orbit. An abort to the middle of the Atlantic ocean is understandably not acceptable. Watching the OFT-2 ...
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1 vote
20 views

### NASA GMAT Hardware in the Loop testing

We are currently evaluating various Mission Analysis & Simulation tools, one of which is NASA's GMAT (2020). One of our requirements is for the tool to support HITL testing. However, i am unable ...
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1 vote
25 views

### Between two spacecraft, differential phase measurements are used to achieve high relative bearing accuracy. How is this done?

Based on my understanding, as spacecraft A transmits a signal to spacecraft B, multiple receivers on spacecraft B receive the signal. When spacecraft B changes its orientation, the phase differentials ...
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### How many times has SpaceX reused Falcon 9 first stage until now? [closed]

How many times has SpaceX reused Falcon 9 first stage until now? Not about the possibility. I want to know the current progress with the Falcon 9 first stage.
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997 views

### Why was the Atlas V's SRB kept attached for 1 minute after burnout in the OFT-2 mission?

In Boeing's OFT-2 mission, an Atlas V is the launch vehicle. The solid rocket booster burns out at T+ 1:35 minutes, but the boosters are jettisoned at T+ 2:40 minutes. Why are the boosters not ...
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187 views

### Why is my C++ code for an orbit propagator wrong?

I tried making an orbit propagator C++ code. Its values seem to be propagating evenly but still I get a straight line orbit instead of an elliptical one. Why? ...
55 views

### How to calculate the max mass and speed of an asteroid capturable by gravity assist?

After reading this question and the answers, I am wondering about the limits of slingshot method to capture an asteroid into a planet orbit. Is it possible to calculate if an asteroid can be captured ...
• 2,605
42 views

### How do I convert from one local NED frame to another?

A little bit of background in case you are interested. I am running a re-entry simulation, and I am dealing with two different reference frames. The one with the higher fidelity dynamics is in the ...
103 views

### How to plot a satellite's orbit around Earth in MATLAB?

Given orbit height, mass and initial velocity how should I plot a satellite's orbit in MATLAB? I was hoping to use verlet integration (I need to implement a solver) possibly the velocity-verlet. I ...
37 views

### Alodine on Spacecraft External Surfaces?

What type of alodine is used for external coatings on satellites, if necessary? Is it type 1 (hex chromate) or type 2? Is there a disadvantage using type 1?
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4k views

### How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

I'm currently attempting to plan out a mission where, in 2029, during Apophis's close approach to Earth, a rocket is sent up to intercept Apophis and decelerate it, making it orbit the Earth. At it's ...
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1k views

### Are nozzle plugs taken out before launch or are they ejected upon ignition?

Inspired by this question. For most orbital launch vehicles, do their engines have nozzle plugs installed and what happen to them at launch? Are they manually removed during the prelaunch/rollout or ...
• 2,185
310 views

### Helium balloon as a rocket

This question is not about rockoons, which are rockets using balloons as launch platforms to start from a greater altitude. This question asks about using the balloon itself as the rocket, like a toy ...
1 vote
91 views

### After one year exploring Jezero's crater floor, (why) hasn't there been any investigation into the presence of trace elements with PIXL?

PIXL instrument chart sample Credit:NASA/JPL-CALTECH Of course PIXL has been used already in Jezero crater, but as far as I know only to identify mineral compositions and textures, as described in ...
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76 views

### Low-thrust maneuver validation in GMAT

I'm working on a LEO-to-LEO transfer with low-thrust propulsion. I've generated a control sequence with a direct optimization implemented by me and I would like to use GMAT to validate the maneuver. I ...
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115 views

### Is crater counting accurate for relative dating between celestial bodies?

This Planetary Society article explains how crater density per unit area on the lunar surface helps identify what regions are older/younger than others. It also mentions that this chronology can be ...
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45 views

### Is there a significant reason why pintle injectors are only used in single configuration?

All of the resources I've managed to track down thus far about pintle injectors concern engines which only use a single, large central pintle for the entirety (or vast majority) of propellant supply ...
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423 views

### What's this inside the RD-0120?

There is a decent shot of the RD-0120's inside in this video: I guess it's something covering the injector plate or even the combustion chamber since the SSME's injector looks very differently: Also,...
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332 views

### How to find the hyperbolic angle given the mean anomaly?

I'm modelling a hyperbolic gravity assist trajectory around Jupiter and trying to calculate the coordinates for each hour interval before/after passing periapsis. I've calculated $M_h = 0.0176$ is the ...
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57 views

### Which is the primary spacecraft in a conjunction?

I ask the question in the title because I cannot find a clear answer. It seems that in collision avoidance, the primary spacecraft is always more accurately known then the secondary. But I think this ...
155 views

### Why "quiet cruise" of a spacecraft would cost NASA 30 mln \$ a year?

The 2022 Planetary Decadal Survey (Chapter 22) states that "quiet cruise" phase of an interplanetary spacecraft will cost about 30 million dollars a year for NASA. "Quiet cruise" ...
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251 views

### Can something like SpinLaunch actually work?

Can something like SpinLaunch actually work? It appears that Spinlaunch attempts to accelerate a capsule to very high speeds and then basically throw it into space. A regular rocket is moving slowest ...
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286 views

### Where can I find an up-to-date report on the Hubble Telescope's orbital history and current altitude?

I haven't been able to find a current report on the state of Hubble's orbital decay and I'm hoping someone can direct me to that info. The satellite tracker sites just present an average or estimate ...
149 views

### Can a human base jump to earth from a satellite? [duplicate]

Only Felix Baumgartner managed to parachute from a helium balloon in the stratosphere is about as close as it gets. But is it technically possible to do so from an orbiting satellite? Advantages is ...
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1k views

### Does the Merlin vacuum engine on SpaceX's Falcon 9 gimbal?

SpaceX uses the Merlin Vacuum engine on the second stage of the Falcon 9 launch vehicle. Does the merlin vacuum engine gimbal or does the second stage uses only nitrogen cold gas thrusters for ...
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### Why doesn’t NASA build its rockets using graphene?

Graphene would be a great material to build a rocket out of. Graphene is extremely thin. One single atom thin layer of graphene can withstand 15 000 000 pascal . A square meter of this material only ...
313 views

### How far is the solar system's center of mass from the sun? [duplicate]

We often say that the planets orbit the sun. But, in reality, they orbit the solar system's collective center of mass. How far is that point from the center of the sun?
71 views

### How does one calculate the look angle for non-geo satellites (i.e. LEO, HEO, etc.)

I'm trying to find a way to calculate look angles to not just GEO satellites, but LEO, MEO, and HEO sats. The only calculator I've found myself is here, which was referenced for a similar problem on ...
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162 views

### Can we use magnets to land a spaceship (Starship)?

Can we use magnets to land a spaceship (Starship)? We could give the landing legs a magnetic flat surface or something and then the controller can reduce the magnetic strength or in other words, ...
107 views

### Was Apollo 8 lunar orbit entry speed intentional at 7,777 ft/s?

When Apollo 8 first went behind the back side of the Moon, it was traveling at 7,777 feet per second (https://history.nasa.gov/afj/ap08fj/12day3_lunar_encounter.html). Was the speed being all 7s (the ...
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125 views

### Could we launch from the moon to another planetary body? [closed]

Would it be possible with currently rocket technology or technology towards the end of its development (ex. SLS, Starship, New Glenn, etc.) to launch from the moon. Of course, we would send down a ...
96 views

### What artificial satellite has the closest stable orbit around the Earth? [closed]

What is the closest Earth orbiting satellite? What is it's speed What is it's purpose? What is it's altitude?
200 views

### Can we launch from the moon?

Would it be possible with currently rocket technology or technology towards the end of its development (ex. SLS, Starship, New Glenn, etc.) to launch from the moon. Of course, we would send down a ...
1 vote
63 views

### Why is most of mission control in Houston? [duplicate]

They were already making a mission control at Cape Canaveral, and then decided to move some, but not all, of it to Houston. Why? Wouldn't it make more sense to have the entire mission control in one ...
74 views

### Apollo ALSEP RTG shorting switch to prevent overheat of the RTG?

I found these lines in the Apollo 14 Lunar Surface Journal: 116:07:37 Mitchell: Houston, the current reading is 8. 116:07:42 McCandless: Understand 8 amperes before pressing the (shorting) switch. ...
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### What was this stationary, then moving light point seen at daylight?

While lying on the garden couch looking straight up I noticed a point light directly above me, similar to a star. This surprised me as it was about an hour before sunset and the sky was still bright. ...
100 views

### Can JWST come in for a pit stop? Is the fuel supply on JWST adequate for a transfer to an Earth Moon libration point to allow repairs?

The James Webb Space Telescope is generally considered unserviceable. This is primarily due to its location. Is it possible for the JWST to use a low energy heteroclinic transfer to reposition itself ...
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741 views

### What is the purpose of the shrouds surrounding these rocket engines?

While researching the purpose of some rocket engine components, I came across several images of perforated shrouds surrounding the combustion chambers of rocket engines. I was highly curious about ...
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### short duration of crew 4 mission

I am wondering why the crew 4 mission is (for the moment) only planned for 4 and half months and not the usual 6-6.5 months? Thanks.
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